1. Field of Invention
The invention relates to a display device and an electronic apparatus.
2. Description of Related Art
Some related art optical display devices, such as liquid-crystal display devices and EL display devices, have a layered structure of multiple circuit elements, electrodes and liquid-crystal or EL elements layered on a substrate. For example, a type of such an EL display device has a sandwich structure of a light-emitting substance-containing, light-emitting layer sandwiched between electrode layers of an anode and a cathode, in which the holes from the anode are recombined with the electrons from the cathode in the light-emitting layer having the ability of fluorescence emission. The device of the type emits light while it is not activated from its excited condition, and this is the phenomenon of the device to emit light.
A related art active matrix driving system can be used to drive the EL display device that has scanning lines aligned in rows and data lines in columns to form a matrix pattern therein and has an electrostatic capacitor element and a transistor disposed for every pixel of EL elements in the intersections of those lines. This emits light in accordance with the voltage that has been charged in the electrostatic capacitor element of every pixel while scanned for writing thereon, and keeps its light emission until the next rewriting on it.
Some display devices that are driven according the active matrix driving system as discussed above have different driving circuits, such as a driving circuit for scanning lines to impart a selected scanning pulse to every scanning line, a driving circuit for data lines to supply a specific data signal to each data line, and an inspection circuit to inspect the display devices for quality and defects during their fabrication and shipping. In such display devices, the driving circuits and/or control circuits must be mounted on their substrate, and this causes various problems in that the substrate is large-sized, and not much of the region having these circuits can be used for the display region of the devices, and the effective display region of the devices is thereby narrowed. In addition, lead lines from a predetermined supply source to the driving circuits and/or inspection circuits must also be mounted on the substrate, and these elements will further narrow the effective display region of the devices.
On the other hand, in case where the panels of such display devices are desired to be enlarged, the number of shift register stages that constitute one general constitutive component of the driving circuits and/or inspection circuits is increased. In such a case, when the devices consume a large quantity of electric power, the power voltage thereto may be lowered. If so, in addition, the supply power to the driving circuits and/or inspection circuits may also be lowered, and this will cause a problem in that the display devices may not operate correctly.
The present invention provides a display device which is free from, or is protected from, errors that may be caused by the reduction in power voltage applied thereto, and provides an electronic apparatus equipped with such a display device. The display device of the invention provides power source lines to the driving circuits and others thereof in a predetermined site of the substrate of the device, and to thereby increase the effective display region of the surface of the substrate.
To address or solve problems noted above, the display device of the invention has, on its substrate, a display region that serves for display and a non-display resin not for display. The display region and the non-display resin are each aligned in a predetermined matrix pattern of barriers and recesses spaced from each other with the barriers adjacent thereto. The display region includes at least a first electrode layer, an essential display layer with a substance switchable for display or non-display therein and a second electrode layer that are aligned around the bottom of each recess in the recess region thereof in that order from the side of the substrate. The non-display region includes at least the essential display layer and the second electrode layer around the bottom of each recess of the recess region in that order from the side of the substrate. The substrate is provided thereon with a switch unit connected to the first electrode layer to control electric conduction to the first electrode layer, an operation control unit connected to the switch unit to control the switch unit operation, and a driving voltage conduction element to drive voltage application to the operation control unit to drive it therewith. The driving voltage conduction element is so aligned as to be at least partly in the non-display region, and in plan view of the substrate, so as to be at least partly superimposed on the recess region.
In the display device of the type, the recesses spaced from each other with the barriers adjacent thereto are aligned in a matrix pattern to form pixels. In the case where the pixels in the display device are aligned, for example, in such a matrix pattern, all of the pixels are not always in the display region (as real pixels) for display service, and instead a part of them may be in a non-display region (as dummy pixels) not for display service. The reason is due to a matter of device fabrication. For example, in case where the essential display layer is formed in the recess region, it is often difficult to make the layer have a uniform thickness, especially at the periphery of the substrate. In such a case, the recess region in which the thickness of the essential display layer formed may be uneven is made to be a non-display region to thereby cancel the display failure, due to the uneven thickness of the essential display layer. The display failure includes, for example, contract reduction, uneven display, and pixel life reduction.
Naturally, the non-display region does not substantially function for image display in the display device, and the region in the substrate is useless for display. Because of that situation, the present inventors have tried and succeeded in forming the driving voltage conduction element for the operation control unit that controls the operation of the switch unit of the device in at least the non-display region thereof for positive effective utilization of that non-display region. Accordingly, in the display device of the invention, the driving voltage conduction element substantially not in display service like the non-display region is disposed in that non-display region, and this constitution cancels out the area of the substrate not in display service, therefore making it possible to prevent or substantially prevent the display-impossible region of the substrate from increasing.
Further, the display device of the invention is so designed that its driving voltage conduction element is below the recess region in the direction of the thickness of the substrate, or the recess region is superimposed on the driving voltage conduction element in the display direction of the device. In plan view of the substrate of this case, the driving voltage conduction element is so aligned as to be at least partly superimposed on the recess region, and a capacitor is formed between the second electrode layer and the driving voltage conduction element via an insulating layer therebetween in the non-display region. In this constitution, therefore, the capacitor may compensate for the voltage reduction at least in the driving voltage conduction element. In this structure, the bottom of each recess in the recess region runs toward the driving voltage conduction element (toward the substrate), and each recess has the second electrode layer around its bottom. Therefore, as compared with the barriers, the recesses in the recess region tend to have an increased capacitance, and their effect of compensating for the power source voltage reduction may be larger than that of capacitors superimposed on the barriers.
Accordingly, the display device of the invention reduces the area of the display-impossible region of its substrate and enlarges the area of the effective display region thereof, and it is free from, or is protected from, errors that may be caused by the reduction in power voltage applied thereto. Organic EL substances can be used for the display substance to be in the essential display layer of the display device of the invention, for example. In addition, liquid-crystal substances can also be used.
Preferably, in the display device of the invention, the barriers are so designed that adjoining two barriers are parallel to each other along the axis thereof, and the driving voltage conduction element is so designed that it includes a part formed between the neighboring barriers to be almost axially parallel to them. In this embodiment, the area of the part in which the driving voltage conduction element is superimposed on the recess region is further increased and the effective display region of the surface area of the substrate is therefore further enlarged, and the effect of this embodiment to compensate for the reduction in the power voltage to be applied to the device may be higher. Also preferably in the display device of the invention, the non-display region may be provided with a first electrode layer between the substrate and the essential display layer and with an insulating layer to block the electric conduction between the first electrode layer and the second electrode layer. In this embodiment, the insulating layer blocks the electric conduction between the electrodes in the non-display region, or makes the electric conduction therebetween in the non-display region more difficult than that in the display region. In fabricating the display device of this embodiment, the electrode layers, the essential display layer and the insulating layer of the device may be formed, for example, through photolithography. In such a case, the insulating layer is formed in the entire recess region, or it is partly opened to have an insulationdepleting layer partly therein. In this case, either the display region or the non-display region may be formed in a simplified manner.
Also preferably in the display device of the invention, the surface of the insulating layer may be formed of a material having an affinity for the essential display layer that is relatively higher than an affinity of the surface of each barrier. This embodiment is almost free from a problem that the thickness of the essential display layer may increase around the barriers, or the essential display layer may be more uniform in this embodiment. As a result, this embodiment will be almost free from a trouble of contrast reduction.
Also preferably in the display device of the invention, the substrate may be provided thereon with multiple scanning lines and multiple data lines formed to cross each other, the switch unit is connected to the scanning lines and the data lines, and the operation control unit includes a data control unit to control the signal to pass through the data lines. Apart from this, the switch unit may be connected to the scanning lines and the data lines, and the operation control unit may include a scanning control unit to control the signal to pass through the scanning lines. Needless-to-say, the operation control unit may include both the data control unit and the scanning control unit. Also preferably, the substrate may be provided thereon with multiple inspection lines, the switch unit is connected to the inspection lines, and the operation control unit includes an inspection control unit to control the signal to pass through the inspection lines. Needless-to-say, the operation control unit may include the data control unit, the scanning control unit and the inspection control unit. In these embodiments, the operation control unit is effective to more efficiently control the signals to pass through the scanning liens and/or the data lines and/or the inspection lines. In such embodiments, these scanning lines and/or data lines and/or inspection lines, and the switch unit are all mounted on the substrate, and therefore effective utilization of the surface area of the substrate for these elements is desired. Because the invention has the specific constitution of the driving voltage conduction element to drive the operation control unit therein, it satisfies the requirement of effective substrate utilization and enables stable supply of driving current to the display device.
In the case where an organic EL substance or a liquid-crystal substance is used for the display substance in the display device of the invention, the essential display layer of the display substance of such a light-emitting substance or a liquid-crystal substance may be formed for the respective pixels (in the recess region) in an inkjet process. In such an inkjet process, the non-display region may be formed in a predetermined region, for example, at the periphery of the substrate surface to prevent or substantially prevent the thickness of the essential display layer from being uneven. Accordingly, in case where the essential display layer is formed in such an inkjet process, the constitution of the invention enables effective utilization of the non-display region of the surface of the substrate.
The electronic apparatus of the invention is equipped with the above display device for the display element thereof. Exemplary electronic apparatus include, for example, mobile phones, wristwatches and various information processors such as word processors and personal computers. Most of such electronic apparatus are driven by batteries, and the constitution of the invention realizes stable power supply to them. Most of such electronic apparatus are small-sized, and the display device of the invention packaged in them enables effective utilization of their display region. Even though the electronic apparatus are smallsized as a whole, the invention ensures a relatively large display region.